How critical are seals and shaft passages for cleanliness in hygienic mixers for dairy applications?
In mixers for dairy products, seals and shaft passages are among the most hygienically critical components. They form the interface between the product space and the environment and, if unfavourably executed, can create dead spaces, gaps and deposit zones in which milk constituents such as proteins, fats and sugars adhere and promote microbial growth or the formation of biofilms.
Dynamic shaft passages in particular are critical for cleanliness, because movement and pressure differences can carry product into the sealing areas or, in unfavourable cases, allow media from outside to enter the product space. A design in accordance with hygienic design principles markedly reduces this risk.
The essential requirements are a dead-space-free geometry, smooth and easily cleanable surfaces and a design that fully supports CIP and, where applicable, SIP. Product-contact surfaces should consist of suitable materials approved under food law and be shaped so that cleaning media reach all areas reliably and can drain completely.
For dynamic sealing, hygienic mechanical seals or suitable lip seal concepts are regarded as the state of the art. Gland packings are generally unsuitable for modern dairy applications because they are not dead-space-free and can be controlled hygienically only to a limited extent.
Wear, ageing and maintenance are equally important. Elastomer fatigue, cracks or surface damage increase the risk of leakage and contamination, which is why defined inspection and replacement intervals are an essential part of hygiene management.
In sum, seals and shaft passages in hygienic mixers for dairy applications are decisive components for cleanliness and safety. Their design, cleanability, material resistance and maintenance act directly on product safety, microbiological quality, shelf life and process reliability.
How amixon® solves seals and shaft passages – hygienic and dust-tight at the same time
The most critical sealing point is eliminated by design
In amixon® mixers the mixing tool is supported and driven exclusively from above. The lower shaft passage, in conventional mixers often the point most critical for cleanliness because product bears against the seal under the pressure of the bulk material, does not exist. Sealing points arranged above the product level are subject to considerably lower mechanical and hygienic loads and can be controlled far better.
Door seal: OmgaSeal® in the Clever-Cut® design
The large inspection doors are manufactured by the Clever-Cut® process and seal permanently dead-space-free with the OmgaSeal® seal. The seal sits in a groove with an undercut, without a crevice to the product space. On request, the doors are executed vacuum-tight or against overpressure, so that hygienic cleanability and dust tightness are met with the same sealing concept.
Rotating passages and fittings
Cutting rotors, for example for de-agglomeration or for the distribution of liquids, run with a mechanical seal, including in pressure-tight and vacuum-tight mixer-dryer reactors that hold a vacuum down to 5 mbar abs. Discharge devices are designed as dead-space-free standard connections with a discharge flap or as vacuum-resistant and pressure-resistant ball segment valves.
Low maintenance as a side effect
Fewer sealing points mean fewer wear parts and fewer inspection points. amixon® supplies selected wear parts together with the initial delivery, and most spare parts are held in stock at the Paderborn site, with a lifetime spare parts service.
A further important advantage is the high dimensional stiffness of amixon® apparatus. Even under maximum load, no perceptible deflection or relative movement occurs. This increases the functional reliability of all seals and contributes substantially to their long service life.
Use in dairy and infant formula
In dairy and infant formula production, amixon® mixers are in use worldwide at manufacturers and contract manufacturers: vitamins, minerals, trace elements, encapsulated omega-3 fatty acids and probiotics are mixed in homogeneously and gently downstream of the spray tower – without destroying agglomerates.
Manufacture in Paderborn as the quality foundation
amixon® develops and manufactures exclusively at the Paderborn works with a high depth of manufacture and all components from Germany. As a certified welding company with European, Japanese, Korean and American qualifications, amixon® designs every apparatus as a one-off on the basis of the operator's URS, and quality control remains entirely in-house without gaps. Every component can still be re-manufactured reproducibly decades later.
Qualifiable and documented
For regulated environments, amixon® supplies the plant ready for qualification. Every apparatus is a one-off to the URS from in-house manufacture with quality control without gaps, and amixon® assists on request with DQ, IQ and OQ. Documentation and execution follow, on request, EU GMP and FDA 21 CFR Part 11, and on request the mixers meet the relevant standards such as EHEDG, FDA hygiene guidelines, 3-A Sanitary Standards, USDA, GMP, ATEX and ASME.
Verification in the amixon® pilot plant
Whether the specific formulation delivers the expected results is verified by amixon® in advance at the pilot plant with 35 test units and trials with the original product under real conditions. The trials are carried out, evaluated and documented jointly and serve as a robust basis for decision-making before the investment. amixon® also runs endurance trials there in connection with national special regulations, the reduction of PFAS in sealing materials and the recyclability of components.